In this 15-week study the effects of motivational email messages on learner self-efficacy and achievement in an asynchronous math course were investigated. A repeated measures design was used. One hundred, ninety-six participants were randomly assigned to control and experimental groups. Specially designed email messages were sent weekly to both groups for 4 weeks. Eighty-six participants completed the study. Self-efficacy to learn mathematics asynchronously (SELMA) was measured at weeks 0, 5, and 14. Achievement was measured at weeks 5 and 15. Statistically significant relationships were found between SELMA and achievement. Within each group, the SELMA measurements taken at week 5 were significantly higher than the other SELMA measurements. No significant differences were detected between the groups. (Contains 4 tables, 1 figure, and 1 note.)